Formwork is used to contain and shape cementitious or other flowable material, such as concrete, during the pouring and setting, or curing, processes. One common use of formwork is in the casting of walls. Once the material has sufficiently set, the formwork is stripped, or struck, therefrom to be reused elsewhere.
Generally, formwork comprises parallel, spaced apart rows of forming panels, with each panel of a row being temporarily connected to an adjacent panel to define a side of the structure being cast. Various mechanisms have been used to accomplish the connection of adjacent forming panels, including complimentary nuts and bolts and complimentary pins and wedges. Unfortunately, these mechanisms generally suffer from a number of problems and disadvantages, including frequent loss of loose pieces and longer time and increased labor costs associated with engaging and disengaging the mechanisms in order to erect and strip the framework.
One such mechanism comprises a retractable pin and latch. When it is desired to connect adjacent panels, the retracted pin associated with a first panel is extended through a corresponding hole in the second panel. Often this is accomplished by striking the opposite end of the pin with a hammer to drive it through the at least partially aligned hole. Even in some of the most advanced apparatuses, momentum prevents the latch from properly securing the panels and the worker must manually engage the latch, with one side fitting snugly around the inside adjacent edges of both the first and second panels to prevent the inadvertent retraction of the pin and disconnection of the panels. Another step is required to move the lock into a latched position. When it is desired to disconnect adjacent panels, the engaged latch is first manually disengaged, i.e., pried up and above the inside edges of both the first and second panels to provide sufficient clearance; the pin is retracted from the corresponding hole by striking the end of the pin with a hammer. Because the pin is not connected to a housing structure, the pin occasionally bounces back and multiple strikes are required. Another problem that results from a lack of attachment to the housing structure is the pin often falls out of place and is easily lost. Because the pins must be longer within the housing to avoid this issue, the latch often does not travel far enough to properly secure the panels. This is also an issue when it is desired to retract the pin and stow the latch because the pin often does not retract all the way through the openings, or bounces back requiring several strikes. Also, these types of assemblies often do not allow the engagement pin to travel back through both panels and the worker must rotate the panels apart to effectively strip the framework. Finally, the latch is manually stowed by rotating the latch towards the now poured cementitious or other flowable material. It will be appreciated that this process requires several steps and wastes significant labor time by requiring multiple strikes and time spent looking for missing pieces of the assembly. In these and other devices, it has been generally viewed as an disadvantage to use elongated pins, or pins with increased tapering of the forward end, for initially securing the panels, both due to cost and increased mushrooming of the tip of the engagement pin. Although these assemblies are often described as one-step mechanisms, in actual use, these mechanisms often involve many additional steps, as described above, to accomplish the same goals as the present invention.